The big doesn't scare easily but, like all of us, scare occasionally he does. Right now, as he contemplates The Open Championship, it is at least a fair bet that Ernie Els is more than just a little frightened. Not of what might happen up on The Wirral at Hoylake but of what has happened already and his failure so far to overcome it properly.

A year ago Ernie was in his usual carefree state. On holiday with his wife and kids, he was fooling around on a boat in the Mediterranean when he tried to turn his 6ft 3in frame. As his body swivelled, his left leg stayed rooted to the spot and the pain when it hit dropped him like a stone. Els had ruptured his anterior cruciate ligament.

Now, though the pain has gone, this trivially inspired but freakishly serious injury is threatening to end the really significant part of a career that has marked out this genial South African as a truly wonderful golfer, a winner of three majors to date - two United States Opens and one Open Championship.

'I had two ops on the knee, not one as some people think,' he says. 'Well, when I was doing the rehab and all that tough stuff I really wasn't thinking that what had happened that day to my knee was anything close to career-threatening, that didn't occur to me at all, man. Not at all.

'But when I started playing again I was amazed at how my brain wouldn't let me get over on to my left side in the swing. I was trying like hell to make that big move that is crucial in this game and my head wouldn't let me. "Do that and it will hurt" was the message from my brain and I have struggled to overcome it. It's crazy, man, and it's really frustrating me.'

This frustration shows at times even in a sportsman who is more grounded than the majority and whose idea of a good time is a beer and a laugh with mates. It shows in the pain that flashes across his face like a dark cloud scudding into an otherwise sunny day. Ernie Els has worked for what he has, what he is, worked hard and looked after himself, but what he is not used to is encountering a problem that will not bow to his stern will.

Games have always been easy to him. He was an outstanding young tennis, cricket and rugby prospect before golf overwhelmed the rest and by the time he hit scratch as a 14-year-old he knew what he wanted to do with his life. This he has done brilliantly. As a global golfer he is without peer, picking up the torch of travel from Gary Player and refusing to tie himself down to any particular circuit. 'I've enjoyed the travel, the different experiences. I respect other guys who want to stay in one country, but that's not for me. I suppose I like to be my own man and to see for myself what's out there.'

What is out there next week, of course, is the year's third major and the most significant test to date of where Els' head is in relation to his knee. Only a one-eyed fool suffering a particularly challenging day would edge his way towards declaring the end of a talent as sublime as Ernie's. On the other hand, desperation does not sit easily alongside a man who is used to bending much to his will. How he performs at Hoylake will go a long way towards defining his future.

Els admits that at 36 he has maybe 'five years left to continue competing at the top level', but he insists that he is 'in better shape than when I was in my twenties' and, of course, he believes that he is 'close to being really ready again'.

Those of us who have enjoyed not just his golf but his company over the past decade hope he is making a careful judgment on all this rather than declaring an act of blind faith. Whichever, the indisputable fact is that the statistics tell a worrying story. In golf, these stats can confuse as much as they illuminate, but the really relevant one after you scrape all the blather aside is the category marked 'stroke average'.

It is here that Els is wounded, for his present average 70.19 per round is more than a shot worse than a couple of years ago. In this game this decline is close to terminal, for when a golfer adds four or more shots to his 72-hole total he drops from contender to a top-20 man. Until now, Els never has been a top-20 man and this is the really frightening thing as he approaches Merseyside.

Perversely, life away from competition has never been better. Happily married and a doting father, Els has spent the past year launching a series of commercial enterprises that include his own wine label, a range of luxury leathergoods, a clothing venture in company with Andrew Flintoff and, of course, his course-design company.

'Basically I'm trying to take care of my future man,' he says. 'But I've got a lot of golf to play before, that's the central part of my life. The Open? I've got to think I've a chance at Hoylake. I played there twice as an amateur and loved the place. I won one of those tournaments and so I know I can play it.'

Or at least he knows he could. Back then he did not know the meaning of the word 'fear'. He does now.